1. Field of the Invention
The present invention relates to a power system stabilizer and a power system stabilization method capable of stabilizing the operation of a power system.
2. Description of the Prior Art
A power system stabilizer to be used in a generator excitation system for improving the stability of power system is often referred to as a PSS. Basically, there are a P type PSS and a .omega. type PSS. The P type PSS inputs a deviation value .DELTA.P (as an input signal indicating a difference from a reference value) of the active electric power of a generator. The .omega. type PSS inputs a deviation value .DELTA..omega. (as an input signal indicating a difference from a reference value) of the rotational speed of a generator.
Both the PSS generate a control signal corresponding to the input signal and outputs the generated control signal to an automatic voltage regulator (AVR) for a generator in order to suppress the oscillation of active electric power, a terminal voltage potential, and other values of the generator in the power system.
Because the conventional power system stabilizer has the configuration described above, it is possible to suppress the oscillation of generators connected to the power system efficiently when there is no change of operational conditions of the power system. However, if operational conditions of the power system are changed and the oscillation with the frequency modes out of the designated range occurs, it is difficult to suppress the oscillation caused in the power system.